The invention relates to headsets having ear domes adapted to attenuate noise. Such headsets may be used with communication equipment as well as ear protectors and other similar noise attenuating devices. The invention particularly relates to ear seals for use with such headsets.
Headsets typically function by enclosing the ears of a user within earcups such as plastic domes. Comfortable ear seals are interposed between the earcups and the user""s head to assist in isolating the ears from offending noise originating outside the earcups. The earcups are typically attached to a spring and suspension assembly that applies a force urging the ear seals in place against the head of a user. The difficulty in providing improved noise attenuation without detracting from comfort has been long recognized. See for example, U.S. Pat. Nos. 6,163,615; 5,293,647; 4,944,361; 3,571,813 and 2,408,494.
The ear seals that are interposed between the earcups and the user""s head are known to be formed of a variety of foam materials, including sponge plastic and foam rubber (see U.S. Pat. No. 3,593,341), highly compliant foam (see U.S. Pat. No. 4,922,542), polyurethane foam (see U.S. Pat. Nos. 4,958,697, 5,020,163 and 5,148,887) and scythed urethane foam (see U.S. Pat. No. 6,295,366). Ear seals made of these foam materials are known to be formed in a variety of shapes.
Flowable materials such as liquids and semi-solids are also known to be used in ear seals by enclosing the flowable material in a flexible sealed enclosure. Conventional flowable materials used in such ear seals include liquid glycerine (See U.S. Pat. No. 4,674,134), nonliquid silicone gel (see U.S. Pat. No. 4,856,118), and a liquid mixture of dilatent silicone compound and a silicone oil (see U.S. Pat. Nos. 5,138,722, 5,911,314 and 5,821,468). Although the foam material is known to be formable into a variety of shapes, flexible sealed enclosures for containing flowable material have typically been formed as pliable annular rings that may closely conform to a users head.
It has been found that foam ear seals do not sufficiently exclude ambient noise in certain applications, and ear seals including a flowable material within a flexible sealed enclosure may permit a small amount of ambient noise to enter the dome cavity in certain situations. For example, during use a flexible sealed enclosure may develop creases in the surface that contacts a user""s head. If any of these creases extend from within the ear dome cavity to the outer peripheral edge of the ear seal, then such creases may form channels through which ambient noise may enter the ear dome cavity compromising noise attenuation.
It is conventionally believed that the material used for the flexible sealed enclosure should be thin, soft and pliable so as to adjust itself well to the shape of a user""s head. See for example, U.S. Pat. No. 4,674,134. It is also conventionally believed that if the exposed surface of the ear seal is irregularly shaped, any irregularities in the shape should be constrained from unwanted irreversible movement. For example, although U.S. Pat. Nos. 4,856,118 and 4,989,271 disclose the use of two concentric annular cavities for containing a silicone gel, U.S. Pat. No. 4,989,271 discloses that the base of the groove between the concentric annular cavities should be sealed to an inner ring to prevent the groove from inverting due to undesired movement of the gel during use. Such ear seals including two separately secured annular cavities for containing silicone gel, however, have not been found to provide sufficient noise attenuation in certain applications.
There is a need, therefore, for an improved ear seal for headsets that provides sufficient noise attenuation and comfort.
The invention provides an ear seal for use in a headset. The ear seal includes a flexible sheath that encloses and is in contact with flowable material. The flexible sheath includes a first surface extending between inner and outer peripheral edges of an annular top. The first surface is adapted for contacting a user""s head and includes an inner annular groove separating an inner annular surface portion from a crease inhibiting central annular surface portion, and an outer annular groove separating an outer annular surface portion from the crease inhibiting central annular surface portion.